1. Field of the Invention
The present invention relates to an image processing apparatus for reading an original put on an original plate (or copyboard) of an image reading apparatus, processing thus read image, and outputting. More particularly, the invention relates to an image processing apparatus for trimming only an image area of an original put on an original plate and outputting.
2. Description of the Related Art
An imaging scanner, a multifunction apparatus, and the like can be mentioned as image input devices which are used when data of a paper media is converted into digital data and sent into a PC or the like. Those image input devices can read many various kinds of documents such as monochromatic image like a character original or the like, color image like a magazine, developed photograph, and negative and positive films.
In the case of reading the original, according to a method in the related art whereby the user designates a reading range of the original plate and reads the original on the original plate, there is a case where the user designates the reading area including a range out of an area of the original to be read. To avoid such a problem, such a function that a range of the area to be read is discriminated from a result obtained by analyzing image data derived by reading the whole original plate and the image data of the decided portion is trimmed and output as an area of the original, has been proposed.
Further, such a function that when a plurality of originals are put on the original plate in a lump, an area of each original is trimmed from image data obtained by reading a rectangular area including all areas of the plurality of originals on the original plate and output, has been proposed. Such a function that a rectangular area of each of areas of a plurality of originals is read and images of the originals are output, has also been proposed.
In those functions, it is important that the area of the original to be trimmed is precisely discriminated from the image data obtained by reading the original plate. According to a general discriminating method, luminance and saturation of the read image data are calculated, an edge extraction and a threshold value process are executed, and an original area and a non-original area in the read image data are discriminated. In this case, if there are very similar a color of the original and a color of parts of an image reading apparatus serving as a background of the read image data, since the luminance and saturation of the original area in the read image data and those of the non-original area, discriminating precision deteriorates. If the threshold value upon reading is changed and it is intended to discriminate the original area from the non-original area in which their luminance values or their saturation values are very similar, there is a case where it is determined that noises existing in the read image are the original area.
As a method of precisely discriminating the original area from the read image, a method whereby a pattern is formed to parts of the image reading apparatus serving as a background of the read image, thereby discriminating a reading target area from other portions, has been known as Japanese Patent Application Laid-Open No. 2001-268367.
A method whereby an image in a state where no original is set is previously held and a difference between the held image and a read image is calculated, thereby determining a reading target area, has been known as Japanese Patent Application Laid-Open No. 2006-048626.
However, there is such a problem that if the pattern is formed to the parts of the image processing apparatus, working costs are needed. In the case of preliminarily holding an image in an original-absence state, a memory to hold the image is necessary. Further, there is such a problem that in association with the deterioration of the image processing apparatus, it is necessary to newly read and set the image in the original-absence state, efficiency is low, and usability is also low.